“Help! I can’t straighten my knee!”

For years now, I’ve extolled the importance of working on knee extension 1) after knee injury 2) after knee surgery. This has been particularly emphasized in my reconstructive ACLand meniscus injury writing.

However, not everyone who has trouble with this is in the first month of ACL recovery, or has an ACL history. Losing knee extension is common in practically every knee injury. Whether a good sprain, a scope procedure (arthroscopic surgery), or a knee replacement. It’s the first thing lost, and the first, and most important, thing to gain back.

I wanted to put something together to help a broader group of people suffering from this malady. I do have a good amount written on the importance of working on knee extension, but I don’t think I’ve done a good enough job detailing how to do this. Nor why it’s so crucial to focus on immediately. (Hence, this post, which is posted the same day as this.)

This manual, Regaining Knee Extension, will cover the A – Z on recovering lost range of motion. If you can’t straighten your knee, this should help.

You can get it here-

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What’s covered:

-What is full extension?

-> Full extension is not only the ability to straighten your leg. You want more than that. Brief words on why.

-Why is it important?

-> Sure, there is the obvious benefit of being able to straighten the leg. But why is this so crucial, so early? (More info below too.)

Note: This is not anatomy heavy or technical stuff. I think some rationale for why you’re doing something often helps, but the point of this manual is “What do I do?” and “How do I do it?” opposed to “Why do I do that?” The point of this manual is to get to work, and get healthy. Not to learn the finer points of physical therapy for the knee.

—Compensations

-> When you can’t move your knee like normal, other body parts need to move more. If you can’t straighten your knee, something else has to straighten more. A couple animations are shown illustrating how something like the back can start to get ticked off when the knee can’t move like usual.

–Timing matters

-> I cover this for free here.(Does get a little anatomy heavy.) I can’t emphasize this aspect of things enough. When it comes to flexibility, strength, exercise, and things part of the physical activity world, there really is very little which is time sensitive. Few weeks of bad eating? Eh, no big deal. You’re back on track within the month. Month of no exercise? Eh, not great. But in a week you’re back in the swing.

Not with knee extension though. Time matters. It’s not like every second matters. But days easily turn to weeks, and once you’re at a week or two…things start getting harder.

-How to do it-

–Massive caveat

-> This is in the manual as well, as it bears repeating:

“First, if you’re someone recovering from a knee replacement, this may work, but it may not. With a knee replacement, you always have to consider hardware placement as an impediment to range of motion. Some have to have a revision surgery in order to regain full range of motion.

Second, if you’re someone whose knee has locked on them, someone where you feel something physically blocking your knee from fully extending, like something has moved and is now in the way, this will either not work as well, or not work period. You should see an orthopedist ASAP, and likely get into surgery ASAP. (The emergency room probably won’t do anything though.)

That is often a displaced meniscus tear, and short of being able to get the meniscus to reduce (go back into place, which is sometimes pure luck), that thing isn’t going to budge, nor do you want to force it to. You can still work on things in this manual very carefully, but know full extension is not happening until that blockage is taken care of. Get into an ortho immediately. If you tell them what’s going on -it’s better to do it in person with crutches than on the phone- they will likely fit you in as an urgent appointment.

This is not something to mess around with. You don’t want to be waiting a month or two to take care of something like this. Once it’s taken care of, this manual should work quite well!“

–The goal

-> How quickly are we trying to get this extension back? How soon is reasonable?

—Caveat to the goal

-> Making the distinction between those who were recently injured, and those who haven’t had full knee extension for a while.

–Regaining passive extension

-> Including a video going over the main exercise to regain extension. No special materials or equipment are needed.

–Regaining quadricep activation

-> It’s common for the quadricep to fall asleep after knee trauma. The quadriceps help extend the knee, so we want to insure they’re awake.

–Regaining active extension

-> Discussing why we start with passive extension and quadricep activation first, before moving on to active extension. Again, no special equipment is needed. Whatever you have around your apartment / house will suffice.

Passive extension is something else doing the work. Gravity, a weight, a person; active extension is the leg doing the extending.

-Making your daily life more extension friendly

-> You have a good idea of what to do exercise wise, but how do you go about your day? You can exercise and work on your extension for an hour everyday, but if you’re stiffening things up the other 23 hours, you’re fighting a battle you don’t have to.

–Sitting

-Laying down (and sleeping)

—Waking up in the morning

–Standing

^ Modifications for all the above to help make one less likely to lose extension.

-Checklist: How a typical day might look

-> I go through an imaginary day, hour by hour (sometimes minute by minute), detailing how to make sure you regain full extension. This will encapsulate everything discussed beforehand, but with an example of how to implement it into daily life.

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The manual is $12:

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Brian, nice to see you producing something specific on knee extension… I’ll be purchasing the manual over the weekend!

Despite constant work on extension since my ACLR (+ meniscus), frustratingly it is still coming and going. There is a bit of ‘junk fluid’ floating about within the knee that both my physio and surgeon say to not be worried about, that it will (continue to) process out as the leg gets stronger and the rehab progresses, But it does seem to be getting in the way of the extension as i can feel and see it shift about as the knee moves through its ROM. I haven’t seen you mention anything like this in any of your posts? Is it something that you have ever came across?

As per my most recent surgical review (3 months), I’m at -5degs (after ‘warming-up’) compared to my ‘good’ leg, which is -8degs. Before i train, etc, I’m not getting any hyperextension at all. I’ve gotten a lot of relief/success recently with this https://www.youtube.com/watch?v=2ENgwxb4zFA but it is something that I’d really like to finally get on top of at this stage, as-in, finally get it (where i want it), and keep it, especially as my rehab moves towards the more ‘sporty’ phases!!

My desk job and daily routine I’m thinking is starting to become an issue also; I’m desk bound for most of the day, or else I’m out of the office driving.

Again, keep the intel coming anyway; your site has been a great supplement to my rehab!

-I’ve seen a variety of things when it comes to fluid. From it moving from the knee to the shin, from there being so much you can put an indent in it, from it rushing downward after laying down for a while. I don’t think any of these things are that uncommon. Many who’ve had a bad ankle sprain can probably relate to this stuff.

I address this some in the manual, but I’m unaware of anything fluid oriented which prevents full knee extension. It’s why you can regain it immediately post-op. With flexion, the fluid can e.g. be enough the back of the knee can’t physically move anymore. The knee is literally bigger. That full knee flexion with fluid is not full knee flexion without, and there is no way around that until the fluid is out of there. That’s why it can take a while.

I don’t think there is any need to add a band. Not saying it hurts anything, but I don’t think it’s worth bothering with.

-Ironically, after saying “we want some hyperextension,” he makes the remark “you’re not going to hyperextend your knee” (due to the floor). As he said though, you *want* to regain hyperextension. You *want* to be able to hyperextend your knee. The foot should be elevated in what he’s trying to do, so there is room for the knee to fall into some hyperextension. That’s a big, big hindrance in what he’s doing.

-He also makes the remark “that’s how you know you have normal range of motion” while he’s hyperextending the knee on the floor, by lifting the leg.

1) This will be insanely hard, likely impossible, for many fresh out of surgery, or those who have been lacking knee extension (he doesn’t seem to be proposing that method, I just wanted to make that known).

2) This is assuming everyone has the same starting point. I also address this in the manual, but the best way to know what *your* normal ROM is, is to use the healthy leg as a barometer. Not everyone has the same amount of hyperextension. Some people don’t have any. Trying to regain hyperextension, or too much, when you congenitally have non, or not little, is not a good move. This may seem pedantic, but with this stuff we’re often talking about numbers as small as 5 degrees. Semantics matter.

-I don’t like the forcing the leg down aspect. Where you are pushing the leg into the ground. I prefer to let something else do this. Like gravity, or a small weight -> Passive vs active motion. I prefer passive to start with this. Once full passive is attained, then some active can be thrown in.

-I’m not sure why he’s focusing on tibial internal rotation so much.

-Being seated can make it tougher to regain full extension. I prefer to do this laying down. It helps a person relax more, and it lessens the tension on the hamstrings, so that way you don’t have to worry about a muscular component preventing full extension. (Hamstrings are knee flexors.) What he’s doing in that video, by having the person not only somewhat seated (which can be ok), but having the person then lean forward to push on the knee, is going to really tension the hamstrings, which can cause the knees to bend. It can take a month or more to loosen up stiff hamstrings. You want to be starting with working on strictly the joint here. Loosening the hamstrings can be done in other ways.

I hope so too! I’ve had some good success getting people some knee extension back after not having it for a while. I’ve seen some improve after going multiple years without it. But the longer you go without it, the tougher it gets. Get to work!

Hi Reddyb, I had a weird situation happen, Jan 31,2015 locked my right knee had a displaced lateral meniscus tear, was waiting for Ortho appt 6 days later. I didn’t move out of bed because of the intense pain and ended up getting a massive blood clot in lung. Surgery was postponed for knee till I got strong, as I had strained my heart with the clot. So I walked around 6 months with 15 degrees flexion on the locked knee. Finally had surgery Aug 2015 and had the meniscus removed. PT was more worried about me getting my flexion back because of contracture. I have full flexion. Whoopee. (rolls eyes) My full knee extension is a mess. I’m lacking 7 degrees extension. When walking my heel strike to the ground is short. Saw the doc said I should keep stretching my calf and hamstring. I finally have 50% muscle back in leg, quads yes, vmo can’t see much it. Just wondering since your post is about ACL, would the regaining knee extension exercises work for me? I have started some of them and it helps alittle then it goes back to same extension. Over time this has done a number on my left knee because of over compensation. Your response would be appreciated. Tia

Sorry to hear about your history. Getting a blood clot is a tough experience. Also sorry to hear your PT made the mistake of focusing more on flexion than extension.

This manual would be right up your alley though. One reason I made this is for those having issues with extension but aren’t necessarily ACL people. Mensicus people being one of the main populations who have trouble with this.

Thanks Reddy for your reply. My left knee has been hurting from over compensation/imbalance and also left hip as well. It will be 1 1/2 years since my right leg has been fully extended with some hyperextension. I have been doing some of the knee extension exercises you’ve suggested and slowly I am getting back my knee extension (big smile). Also it tends to hurt less on my left knee as my body mechanics is probably getting more balanced. (just a guess) Although I have noticed my knee tends to slip back to its memory of alittle flexion, maybe because of not enough muscle strength, not sure, but continue with the exercises. Wondering if I would have to do these extension exercises for the rest of my life maintain the extension? Thanks again for your blog its very helpful.

This isn’t something I find people usually need to keep up with forever. Once someone has full ROM in this regard for maybe a few months, I find it tends to stick. I’ll often have people still keep up with it some, maybe once a workout, or once a week, but it’s more as an insurance policy than a need.

There are exceptions though. For instance, the person who has full range of motion but perhaps is doing something which regularly swells their knee some (maybe pushing too much / too soon after a surgery), that person needs to keep up with things because the act of inflammation / swelling may decrease their ROM again. (And they should really be examining whatever it is causing the routine swelling as well.)

I tore my ACL and Class 2 MCL sprain along with tibia spine avulsion while skiing. I did not have surgery, but have been in physical therapy since injury Dec.16,2016 to present. After 3 months I still cannot fully extend my leg and have pain when trying to straighten. At home I use 2 pound weights and hang off a hard surface which I find almost unbearable. I go to the gym 3 x a week to strenghten my quads, hamstrins and glutes and do Pilates 2x a week. None of this is helping my recovery. My PT thinks there is a blockage keeping the leg from straightening. My ortho says to give it more time. I’m not only frustrated, but wonder if it will ever return to normal. Your thoughts are greatly appreciated.

The ortho, through their hands and imaging, should have a *very* good idea if something is blocking the knee, such as a torn meniscus. That typically punches one in the face with its obviousness. However, nothing is guaranteed until an arthroscope is put in there. (You can never be sure what’s going on in a knee until you look inside it.) From a patient point of view you usually feel the blockage too.

I’m not a fan of the hanging off a surface stretch. (Believe you’re talking about the on your stomach version.) Mainly because of what you’re mentioning- it feels crappy.

A huge thing with trying to improve range of motion in this manner is doing so in a manner which is relaxing. One cannot be tensing, and if you’re in pain, then you’re tensing.

It may feel uncomfortable at times, but it shouldn’t be unbearable, make one grit their teeth, feel like crying, or anything like that. It should be “Ok, that was enough.” Then a minute or two later “Ah, that feels good now. I’m glad I did that.” Opposed to “Damn, I’m really not looking forward to doing that again.”

This is all covered in the manual if you want to take a look. Things like strengthening or pilates, while useful for other reasons, are futile range of motion wise.

I’m 12 weeks post op from knee arthroscopy for debridment/loose body. This was my 2nd surgery in 5 years. I’m only 47 but overweight and apparently have arthritis in the knee (I don’t really feel it..). I did fall hard on this knee 20+ yrs ago.

The first time I had the debridment was 7/2013. I did PT the week after per my request. This time, I didn’t. I don’t know why. Doc didn’t mention it and I just didn’t pursue. At my 6 week post op, still couldn’t fully extend knee/leg so I he suggested PT.

The PT is having me lay on table and hang leg off table for so many seconds then bend a few times, rinse repeat. She’s added some weights occasionally too. It doesn’t feel great but tolerable. I’m also doing 2 others exercises to strengthen my quad. Despite the discomfort, I generally feel better afterwards but can feel some discomfort and stiffness the next day. I also feel this discomfort after walking a lot post surgery.

Is this the direction I should be going in PT?
I’m ok with the process moving a little slow and I have lost 15lbs and counting. I’m just a little concerned bc it’s been 12 weeks now and I get a little anxiety worrying about it :-/. Doc did say he removed a lot of inflammatory tissue and he wasnt surprised at 6 weeks that I was still having issues.

No PT after a “knee cleanup” is fairly common, but ideally, after any surgery, some rehab work is done. Primarily range of motion work, as you’re seeing. Like you mentioned, the inflammation can be enough to disrupt range of motion for a while, to where once the person gets the inflammation under control, they still need to work on the range of motion.